﻿/*
Average 
Time Limit:1000MS  Memory Limit:32768K


Description:
It is said that 90% of frosh expect to know average in their class. You are to provide a reality check.

Input:
The first line of standard input contains an integer C, the number of test cases. 
C data sets follow. Each data set begins with an integer N, the number of people in the class (1 <= N <= 1000). 
N integers follow, separated by spaces or newlines, each giving the final grade (an integer between 0 and 100) of a student in the class. 
Output:
For each case you are to output a line giving the average of their class, rounded to 3 decimal places. 
Sample Input:
1
3 1 2 3
Sample Output:
2.000
*/
#include <iostream>
#include <iomanip>
#include <numeric>
#include <algorithm>
#include <vector>
using namespace std;
int main()
{
	int n;
	cin>>n;
	while(n--)
	{
		int m;
		cin>>m;
		vector<int> decimals;
		decimals.reserve(m);
		while (m--)
		{
			int decimal;
			cin>>decimal;
			decimals.push_back(decimal);
		}
		double average = accumulate(decimals.begin(), decimals.end(), 0.0)/decimals.size();
		cout<<fixed<<setprecision(3)<<average<<endl;
	}

	
	return 0;
}